Karrie is right on how children reciprocate the behaviour of parents/teachers.
There was an interesting experiment done on human children and some great apes, bonobos I believe.
In the first set up, there is a puzzle box. The teacher taps two rods on top of the box three times each before using the stick to push each rod through the slot they sit in. Then, they tamp a surface through a hole in the top of the box that the rods covered. Then the teacher can open the door in the front of the box, and reveal the prize inside (a treat)
Now, both the bonobos and young humans replicate the process exactly.
But, when the same puzzle box is replaced by one with transparent walls, and the inside can be seen, the bonobos went right for the hatch where the prize was, seeing clearly that there is no need to perform the procedure as in the first test. The young humans would still repeat the whole process.
That's because humans learn by repeating, and by our very nature that repeatability allows us to pass on knowledge, while other apes will not. There is no certainty that an ape who discovers a novel process or invents a new tool, will pass that knowledge onto other apes, where as humans do. We can stand on the shoulders of intellectual giants.
In a certain sense though, Mrgrumpy you are right. You could replace brainwashing rather with teaching/learning for just about anything young kids learn. It's pretty hard to believe in a specific deity without express knowledge, and most kids probably won't actively search out these kinds of answers on their own. That's just how we're wired. More likely they would ask questions to parents and teachers.